"Falling into a well" is simplified from the sentence "falling into a trap, not leading to rescue, but squeezing it". See Tang Han Yu's "Han Changli Anthology • Liu Zihou's Epitaph": "Once you are in a small interest, it is only like hair, and it is better than not knowing each other." Those who fall into traps, do not lead to rescue, squeeze them, and go down to the stones, all of them. ”
Liu Zongyuan was thick and died in 819 AD. In "Epitaph", Han Yu praised Liu Zongyuan's willingness to exchange the Liuzhou he was sent to and Liu Yuxi's dispatch to Banzhou before his death, and at the same time criticized the phenomenon of self-deception in society. Han Yu said: "The poor see the righteousness. However, now there are some people who usually live in harmony, and they all tell each other with heartfelt words, and even weep and swear to death, so that people cannot but believe it. But once there is a small conflict of interest like hair, it will turn away from people. If you fall into the well, instead of pulling a handful, he will squeeze you down and throw stones into the well. For this kind of beast can't do it, and he thinks he has a plan.
Hearing that Liu Zongyuan took the initiative to write a book and was willing to exchange a good place for a noble style like Liu Yuxi, he should know what it means to be ashamed. This is Han Yu's cynical statement, exposing the career of the people at that time.
Later, he described the ugly behavior of "falling into the well" as having a bad character, gloating, and taking advantage of people's danger.